The proposal is to develop and use a mammalian model of chronic hyperthermia. Chronic hyperthermia is defined as a body temperature 2 degrees C or more above normal for the animal, maintained without remission from 48 hours up to 2 weeks in duration. Two different techniques will be used to develop hyperthermia. Initial observations will be made on the sequence of changes in respiratory pattern, blood gases and pH and urine volume and acid-base content that occur during the hyperthermic period. Subsequent experiments will test for alterations in the respiratory control system and in renal function, that might occur as a result of extended periods of elevated body temperature.